[Insight-developers] GDCM eventually replacing DICOMImageIO2

[Miller, James V (Research)]

Another thing to consider.  We should verify that GDCM returns a
volume in the same order as DICOMImageIO2.  I'd have to dig through
the code to determine whether we order head-to-toe or toe-to-head
(though I think it is toe-to-head, or towards positive z).

This should be easy to verify by reading a volume with both readers
and doing a pixel difference to verify they are the same.

Also, for PET data, does GDCM produce float data?  Each image in a
PET series will have a different "slope" and "offset".  These must 
be applied to each image prior to putting them together in a volume.

Jim




-----Original Message-----
From: Lorensen, William E (Research) [mailto:lorensen at crd.ge.com]
Sent: Friday, November 19, 2004 4:52 PM
To: 'Mathieu Malaterre'
Cc: insight-developers at public.kitware.com
Subject: RE: [Insight-developers] GDCM eventually replacing
DICOMImageIO2


Actually, using the filename is not useful. As you say, the names are
arbitrary.

Multiple series in a directory are certainly common. I have not seen
multiple studies although this is certainly possible.

Look at the API for DICOMSeriesFileNames for the handling of multiple
series.

Bill


-----Original Message-----
From: Mathieu Malaterre [mailto:mathieu.malaterre at kitware.com]
Sent: Friday, November 19, 2004 4:45 PM
To: Lorensen, William E (Research)
Cc: insight-developers at public.kitware.com
Subject: Re: [Insight-developers] GDCM eventually replacing
DICOMImageIO2



> For one, the GDCMSeriesFilenames does not seem to handle mutiple series in
a
> directory.This is a common occurrence. The API of DICOMSeriesFilenames to
> handle this is easy to use.

That's definitely one thing on my TODO list. It shouldn't take me long 
to implement it, once I know the choices:

- How do I order when there is a mixture of DICOM serie and DICOM study
- What should I do when both serie/study have the same number
- What is considerer to be the first serie when there are multiple 
series ? Is  it determine by the first DICOM image read...


> Also, in DICOMSeriesFileNames, the sorting of the files can be ascending
or
> descending. This may or not be a useful feature.

Well, I am not convinced this is usefull and could maybe conduct people 
into error.

What's done currently in GDCMSeries is a strategy approach:

- We read all of our images, then try to order following:

1. What I called /Jolinda's/ algorithm, we extract image position, we do 
some math to determine vector normal of 2D plane, and then order accordingly

2. If 1) fail (no image position...) we order using 'Image Number' this 
is a DICOM tag

3. If 2) fail, we do by filenames, hopefully the files are order properly.

For me this make much more sense, since we don't want people starting to 
work on a 3D image 'inside out'. Or worse, since DICOM does not define 
filename convention (see e-film convention), slices could be 
interchanged, putting slices at the wrong place.


Mathieu

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